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Analytical Chemistry.

Behaviour of Alkaline Solutions of Phenolphthaleïn in the Presence of Alcohol. By H. N. DRAPER and C. DRAPER (Chem. News, 55, 133–134; 143–144).—The authors have investigated the conditions influencing the decolorisation of slightly alkaline solutions of phenolphthaleïn by the addition of alcohol; it would appear that dissolved carbonic acid is in the main the cause of the phenoD. A. L.

menon.

Apparatus for Estimating Hydrogen in the Presence of Methane. By F. HOPPE-SEYLER (Zeit. physiol. Chem., 11, 257-267). -This is a modification (figured) of Winkler's apparatus, in which (1) the mixture of gases is collected over mercury; (2) the portion of gas which has been freed from hydrogen by the action of palladium is transferred without loss to a eudiometer for further investigation. After this, the apparatus is ready for a fresh analysis.

W. D. H.

New Method of Standardising Iodine Solutions and of Estimating Sulphurous Acid in the Presence of Thiosulphuric Acid. By W. KALMANN (Ber., 20, 568-570).-If sodium sulphite is employed instead of hydrogen sulphide in titrating iodine solutions (Abstr., 1886, 579), the objections to the method arising from the use of the gas and the deposition of finely divided sulphur are removed. The sodium sulphite must be free from sodium hydrogen sulphite and from sodium carbonate, and a solution containing 15 grams in the litre is a convenient strength to employ. This is added to the iodine solution until it is just decolorised, and the hydriodic acid formed is titrated with decinormal soda, methyl-orange being used as an indi

cator.

Sodium sulphite may be estimated in the presence of sodium thiosulphate, by titrating with normal iodine, inasmuch as sodium iodide results from its action on the latter; so that the amount of hydriodic acid formed, titrated as above, is a measure of the sodium sulphite present. W. P. W.

Volumetric Estimation of Sulphides. By F. WEIL (Ber., 20, 695-697). A reply to Friedheim's criticism (this vol., p. 396) of the author's method for determining hydrogen sulphide in sulphides which are decomposed by hydrochloric or sulphuric acid (Abstr., 1886, 918). Analyses of stibnite were made in the following way: the finely powdered mineral, wrapped in filter-paper, was put into a flask with 50 c.c. of hydrochloric acid, heated in a sand-bath, and the evolved hydrogen sulphide passed into 50 c.c. of a modified Fehling solution, which was diluted with about 100 c.c. of distilled water containing 7 to 8 grams of soda; the filtered solution was made up to 300 c.c., and a portion (25 c.c.) treated with 60 to 70 c.c. of hydro

chloric acid, and titrated with stannous chloride. The numbers obtained in these analyses were: S = 28-38, 28.18, and 28.59 per cent. N. H. M.

Manganese in Steel and Iron. By H. C. BABBITT (Amer. Chem. J., 9, 58-60).—The method is as follows: 5 grams of the sample is dissolved in 50 c.c. of nitric acid (1·20 sp. gr.) and 1 to 2 grams of red lead added together with about an equal bulk of hot water, when it may be boiled for some minutes. After a time, the liquid is decanted, and the residue boiled with fresh portions of hot dilute nitric acid (20 to 25 per cent.) so long as the decanted liquid is coloured by the permanganate formed. The united liquids are filtered through asbestos and the permanganate determined as usual. The presence of lead nitrate does not interfere, and the results obtained are very satisfactory. H. B.

Decomposition of Chrome Iron Ore. By E. DONATH (Dingl. polyt. J., 263, 245).-The finely pulverised ore is mixed with five times its weight of barium dioxide and heated for half-an-hour in a porcelain crucible over a Bunsen burner. A greenish-yellow mass results, which is completely soluble in cold water acidified with hydrochloric acid. The solution contains the whole of the chromium in the form of chromic acid.

D. B.

Bacteriological Examination of Water. By C. W. FOLKARD (Chem. News, 55, 124-125).-A bent tube drawn out at one end and of 1 c.c. capacity is adapted by a cotton-wool plug to a test-tube containing the nutrient jelly; the whole being then sterilised. The sealed capillary end of the bent tube is then passed through a hole in the wall of an india-rubber tube through which the water to be examined is running under slight pressure, the point is broken, and as soon as the bent tube is filled, it is withdrawn, the point sealed in a flame and the water transferred to the test-tube by shaking.

A. J. G. Determination of Organic Carbon and Nitrogen in Waters. By C. A. BURGHARDT (Chem. News, 55, 121-123).—250 c.c. of the water is mixed with 100 c.c. of a standarised solution containing about 10 grams of chromic acid per litre, and 10 c.c. of strong sulphuric acid. The mixture is boiled for hour, diluted to 1000 c.c., and the excess of chromic acid titrated in 100 c.c. by means of standard ferrous sulphate solution; from these data, the carbon is calculated. For the nitrogen determination, part of the oxidised solution is treated with soda and distilled, the ammonia being collected in a receiver containing acidified water. The method, although only in a preliminary stage, appears to work well.

D. A. L.

Decolorising Power of Bone-black. By G. LAUBE (Arch. Pharm. [3], 25, 133).-Good animal charcoal, from which defective pieces have been rejected, is powdered, dried at 110°, and preserved as "normal charcoal." 50-100 grams of caramel (as obtained from liqueur manufacturers) is dissolved in an equal quantity of water, 100 c.c. of alcohol is added, and the volume is made up to a litre ;

after standing some days the liquid is filtered and marked "normal colour." 5 grams of the normal charcoal is heated to boiling with 200 c.c. of water; 10 c.c. of the normal colour is added, and after 10 minutes' gentle boiling in a reflux apparatus, the liquid is filtered through a double-folded filter. 200 c.c. of water is now measured off and normal colour is added from a pipette until the tint is the same as that of the filtrate. If, for example, 21 c.c. of normal colour is required, the charcoal is equivalent to 10-21 c.c.79 c.c. Any other sample of charcoal can now be compared with the normal charcoal. If a sample indicates 5.5 c.c. of the normal colour, its decolorising power in comparison with the normal charcoal will be 70 per cent. J. T.

Quantitative Estimation of Wood in Paper. By C. WURSTER (Ber., 20, 808-810).-Inasmuch as crude wood shavings have been introduced into the paper manufacture, and the paper prepared from them turns after some time yellow and then brown, and finally becomes unsightly, an estimation of the proportion of wood present becomes desirable.

Dimethylparaphenylenediamine imparts a magenta coloration to paper containing wood, but no change is produced with paper prepared from linen or cotton fibre. In order to make this change quantitative, the paper to be examined is moistened, tested with the reagent, and the tint given is compared with those of standard papers tinted and arranged according to scale. As then the oxidation of the dimethylparaphenylenediamine to the red dye-stuff is quantitative, these standard papers can be prepared and estimated by some titrated oxidising solution, such as iodine. A few such estimations are given as examples. V. H. V.

Investigation of Acetyl-compounds; New Method for the Analysis of Fats. By R. BENEDIKT and F. ULZER (Monatsh. Chem., 8, 41-48). The authors use a modification of Köttstofer's process for the determination of the saponification value of fats. The process is carried out by boiling the acetyl-compounds with strong standard alcoholic potash for 15 minutes, the excess of potash is then titrated with standard hydrochloric acid, about half normal. The amount of potash required for the decomposition is expressed as the "saponification-value," that is, the number of milligrams of potassium hydroxide required for the saponification of 1 gram of the acetyl-compound. If the substance under investigation is an acid, a portion of the potash is used up in neutralising the acid; in such cases the "saponification-value" is the sum of the "acid-value and "acetylvalue." The former must be determined by a separate titration with standard potash. This method is applied to the determination of the molecular weights of the higher fatty alcohols and hydroxy-acids; the substances are first converted into acetyl-derivatives and then saponified as above. The authors have also applied the method to the examination of fats, and state that where the fats principally contain hydroxy-acids, it is possible to identify the acid and in some cases to detect adulterations, both qualitatively and quantitatively. The fat

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is first saponified to obtain the fatty acid, and this is then treated as above. G. H. M.

Analysis of Fats. By B. RÖSE (Chem. Centr., 1887, 234).-In order to avoid the imperfections of the methods of Oudemans (J. pr. Chem., 96, 407) and Kremel (Pharm. Centr., 5, 337), for determining acids of the oleic and linoleic series in presence of solid fatty acids, the author has studied the action of lead oxide on mixtures of these acids in ethereal solution. At the boiling point of ether, an excess of lead oxide rapidly neutralises the acids and even partially converts the liquid acids into basic salts, which remain with the insoluble lead stearate and palmitate. The amount of basic salt formed increases with the time. At ordinary temperatures, however, no basic salt is formed, even during a contact of some weeks; whilst the presence of the solid fatty acids does not hinder the complete neutralisation of the oleic acid by the lead oxide. The soluble lead oleate can, therefore, be accurately separated and determined. M. J. S.

Examination of Butter Colours. By H. B. CORNWALL (Chem. News, 55, 49).—The solution of fat in ether is shaken with a solution of potash or soda of such dilution as to be only just alkaline when separated from the fatty layer after a few hours. Annatto and saffron may be looked for in this extract. With sulphuric acid, annatto strikes first a blue or violet-blue, then a green, and finally brownish or somewhat violet colour. These changes of colour are important, as pure butters have been known to give a green coloration, but always without the preceding blue. Turmeric is easily recognised by the action of the alkaline solution. D. A. L.

Estimation of Uric Acid by Potassium Permanganate. By C. BLAREZ and G. DENIGES (Compt. rend., 104, 789-790).-If the solution of uric acid is too strong, the action of potassium permanganate varies with the strength of the solution and the proportion of tree acid.

If the solution contains not more than 1 gram of uric acid in 8000 c.c. the action of the permanganate is regular and is independent of the degree of dilution and the proportion of free acid. 1 c.c. of decinormal permanganate is equivalent to 0.0074 gram of uric acid. The results are the same in hot solutions as in cold. The quantity of uric acid should not exceed 01 gram, and the quantity of free sulphuric acid should be about 3.5 grams. The amount of permanganate required to produce the end reaction with the same volume of water containing the same quantity of free acid should be subtracted. C. H. B.

Volumetric Estimation of Acids in Salts of the Alkaloïds. By P. C. PLUGGE (Arch. Pharm. [3], 25, 45—59).—By using litmus as indicator, the acids in narcotine, papaverine, and narceïne salts can be directly titrated with standard soda solution, and in this respect these feeble bases differ from the strong opium bases. Equally good results are obtained with phenolphthalein as indicator.

In

general, the salts of the alkaloïds can be titrated directly with phenolphthaleïn as indicator, excepting the salts of the volatile bases, conine and nicotine. In the cases of brucine, morphine, and thebaïne, however, a red coloration makes its appearance before the end of the reaction, but a little experience surmounts this difficulty. In solutions of alkaloïd salts (excepting those of the feeble bases), the amount of free acid can be determined by titration with litmus, and the total quantity of acid by titrating with phenolphthaleïn. The difference gives the quantity of acid combined with the alkaloïd, and from this the amount of alkaloid can be calculated. Sundry examples of the application of the foregoing principles are given, in which the purity or otherwise of various compounds is determined. J. T.

Assay of Opium. By- ADRIAN and E. GALLOIS (J. Pharm. [5], 15, 193-197). In 1867, Guilbermond proposed to estimate the mor phine in an aliquot part of the extract obtained from the opium. More recently Doux proposed to modify Regnault's process in the same direction. He treats 50 grams of opium with 200 c.c. of alcohol at 70°, and takes 105 c.c. of the filtrate as representing accurately 25 grams of opium. of opium. The authors hold that to arrive at accurate and comparable results, it is indispensable to take into account, in every case, the amount of water and of soluble constituents contained in the opium. They consider the opium as being composed of water, material soluble in alcohol at 70°, and insoluble residue. The sample for assay is pounded in a mortar; 5 grams is extracted with 50 c.c. of alcohol at 70°, with which it is kept in contact for 12 hours; the residue is then filtered off, dried, and weighed on a tared filter. The loss gives the amount of water and soluble matter, and the amount contained in the portion taken for the morphine estimation is of course deduced. 50 grams of the sample is placed in a tared and stoppered flask with a wide neck, treated with 200 grams of alcohol at 70°, placed in a bath of 25-30°, and frequently agitated. When the estimation of water and soluble constituents is finished, the flask is carefully weighed, and alcohol is added to make up the liquid contents of the flask exactly to 250 grams. After filtering, 200 grams of this liquid exactly contain the morphine from 40 grams of opium; this morphine is precipitated by ammonia, washed with alcohol at 40°, dried, treated with chloroform, and dried again as in Regnault's process, but taking care to wait 36 hours before collecting the deposit. The method requires somewhat more time than Regnault's, but it has the advantage of being applicable to all opiums whatever their composition, and it gives exact results. J. T.

Estimation of Morphine in Opium and its Preparations. By O. SCHLICKUM (Arch. Pharm. [3], 25, 13-32).-The method recommended is founded on that proposed by Dietrich, and depends on the fact that if a not too concentrated solution of morphine salts is mixed with a slight excess of ammonia and half its weight of alcohol, and is boiled down to one-half the volume of the mixture, no precipitation of morphine follows when the original volume of solution is made up by adding water. The perfectly neutral solution thus

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